Colorectal Cancer

Question 1

What are benign and malignant colorectal neoplasias called?

Answer 1

Benign - adenoma (always a polyp)

Malignant - Adenocarcinoma

Question 2

What do all adenocarcinomas start as?

Answer 2

Adenomas - tubular (unlikely to contain malignant cells) - villous (high rish of developing into adenocarcinoma)

Question 3

Describe the function of an oncogene

Answer 3

Normal - promotes cell growth and division

Mutated - causes excess cell growth and division - contributes to cancer

Question 4

What is a tumour suppressor gene?

Answer 4

Normal - suppress cell growth and division

Mutated - allow cell growth and division

Question 5

What does APC (gene) stand for?

Answer 5

adenomatous polyposis gene

Question 6

How is a colorectal cancer described macroscopically?

Answer 6

polypoidal
ulcerative
annular ring around colon which can obstruct it

Question 7

How are adenocarcinomas classified?

Answer 7

• well differentiated - intracellular mucin still present
• moderately differentiated - no intracellular mucin but still organised in glands
• poorly differentiated - no structure at all

Question 8

Describe the stages of Dukes staging

Answer 8

A – tumour not penetrated the whole way through muscular wall
B – all the way through muscular wall
C – local lymph nodes are involved
D – distant mets

Question 9

In TNM staging, describe the levels of T

Answer 9

T1 - submucosa only
T2 - into muscle
T3 - through muscle
T4 - adjacent structures (including peritoneum)

Question 10

In TMN staging, describe the levels of N

Answer 10

N0 - no lymph node involvement
N1 - < 3 nodes involved
N2 - > 3 nodes involved

Question 11

In TMN staging, describe the levels of M

Answer 11

M0 - no distant metastases

M1 – distant metastases

Question 12

How does colorectal cancer spread?

Answer 12

Local structures
Lymphatic
Haematogenously
Transcoelomic (into peritoneal cavity)

Question 13

GIve 2 routes of autosomal dominant inheritance of colorectal cancer

Answer 13

FAP - Mutation in APC gene

HNPCC - Mutation in DNA mismatch repair gene

Question 14

What do FAP and HNPCC stand for?

Answer 14

FAP - Familial adenomatous polyposis

HNPCC - Hereditary non-polyposis colorectal cancer

Question 15

Are there any predisposing conditions to CRC apart from the inherited ones?

Answer 15

Yes
Adenomatous polyps
UC
CD

Question 16

What are the symptoms of colorectal cancer?

Answer 16

Depend where the cancer is:
Rectum – PR bleeding and tenesmus
Descending colon – pain, change in bowel habit, PR bleeding
Right side of colon – iron deficiency anaemia

Question 17

What are the signs of colorectal cancer?

Answer 17

anaemia 
cachexia 
lymphadenopathy 
abdominal mass/distension
hepatomegaly 
rectal mass 
Blood PR

Question 18

How is CRC diagnosed?

Answer 18

Colonoscopy and biopsy #1
Faecal Occult Blood Testing
Barium enema
CT colonography
Sigmoidoscopy

Question 19

What % of CRC does FOBT detect?

Answer 19

70%

Question 20

Who is FOBT not useful in?

Answer 20

symptomatic patients

Question 21

Who is FOBT given to?

Answer 21

50-70yo every 2 years

Question 22

How can CRC present as an emergency?

Answer 22

Obstruction (distension, constipation, pain, vomiting)
Bleeding
Perforation

Question 23

How is CRC treated?

Answer 23

Surgery - primary treatment - only curative
Radiotherapy
Chemotherapy
R&C can be used before surgery to increase the success of the surgery

Question 24

What surgery is available for rectal cancer?

Answer 24

• Abdomino-perineal excision
• Anterior resection
• local excision – removing small cancers via anal canal – not mainstay, experimental

Question 25

What antigen (via blood test) is most commonly used to monitor patients with colorectal cancer?

Answer 25

Carcinoembryonic antigen (CEA)

Question 26

Can a carcinoma of the colon cause a raised carcinoembryonic antigen (CEA)?

Answer 26

Yes

Question 27

Is a cancer of the colon more common in the transverse colon or the sigmoid colon?

Answer 27

Sigmoid colon

Question 28

Is the sigmoid colon or rectum more likely to be affected by cancer?

Answer 28

Rectum - most common site for cancers of the large bowel accounting for 45% of cancers